<!-- NOTE: spaces differ from Chrome/Firefox (8px vs 4px) because of a different font (Terminus 16px vs Times New Roman 16px) -->
<!doctype html>
<style>
div {
	display: inline-block;
	border: 1px solid black;
	padding: 4px;
}
#a { padding: -10px } /* invalid */
#b { padding: 10px }
#c { padding: 10px 20px }
#d { padding: 10px 20px 30px }
#e { padding: 10px 20px 30px 40px }
#f { padding: 10px 20px 30px 40px 50px } /* invalid */
</style>

<div id=a></div>
<div id=b></div>
<div id=c></div>
<div id=d></div>
<div id=e></div>
<div id=f></div>